Intrinsic structure perspective for MIPS interfaces in two-dimensional systems of active Brownian particles

Suspensions of active Brownian particles (ABPs) undergo motility-induced phase separation (MIPS) over a wide range of mean density and activity strength, which implies the spontaneous aggregation of particles due to the persistence of their direction of motion, even in the absence of an explicit att...

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Autores: Chacón, Enrique, Alarcón, Francisco, Ramírez, Jorge, Tarazona, Pedro, Valeriani, Chantal
Tipo de recurso: artículo
Fecha de publicación:2022
País:España
Institución:Universidad Complutense de Madrid (UCM)
Repositorio:Docta Complutense
Idioma:inglés
OAI Identifier:oai:docta.ucm.es:20.500.14352/71494
Acceso en línea:https://hdl.handle.net/20.500.14352/71494
Access Level:acceso abierto
Palabra clave:539.1
Pressure
Física nuclear
2207 Física Atómica y Nuclear
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spelling Intrinsic structure perspective for MIPS interfaces in two-dimensional systems of active Brownian particlesChacón, EnriqueAlarcón, FranciscoRamírez, JorgeTarazona, PedroValeriani, Chantal539.1PressureFísica nuclear2207 Física Atómica y NuclearSuspensions of active Brownian particles (ABPs) undergo motility-induced phase separation (MIPS) over a wide range of mean density and activity strength, which implies the spontaneous aggregation of particles due to the persistence of their direction of motion, even in the absence of an explicit attraction. Both similarities and qualitative differences have been obtained when the MIPS is analysed in the same terms as a liquid-gas phase coexistence in an equilibrium attractive system. Negative values of the mechanical surface tension have been reported, from the total forces across the interface, while stable fluctuations of the interfacial line could be interpreted as a positive capillary surface tension; in equilibrium liquid surfaces, these two magnitudes are equal. We present here the analysis of 2D-ABP interfaces in terms of the intrinsic density and force profiles, calculated with the particle distance to the instantaneous interfacial line. Our results provide new insight into the origin of MIPS from the local rectification of the random active force on the particles near the interface. As has been reported, this effect acts as an external potential that produces a pressure gradient across the interface, such that the mechanical surface tension of the MIPS cannot be described as that of equilibrium coexisting phases; however, our analysis shows that most of that effect comes from the tightly caged particles at the dense (inner) side of the MIPS interface, rather than from the free moving particles at the outer side that collide with the dense cluster. Moreover, a clear correlation appears between the decay of the hexatic order parameter at the dense slab and the end of the MIPS as the strength of the active force is lowered. We show that, using the strong active forces required for MIPS, the interfacial structure and properties are very similar for ABPs with purely repulsive interactions (the Weeks-Chandler-Andersen-Lennard-Jones (WCA-LJ) model truncated at its minimum) and when the interaction includes a range of the LJ attractive force.Royal Soc ChemistryUniversidad Complutense de Madrid20222022-03-3020222022-03-30journal articlehttp://purl.org/coar/resource_type/c_6501info:eu-repo/semantics/articleapplication/pdfhttps://hdl.handle.net/20.500.14352/71494reponame:Docta Complutenseinstname:Universidad Complutense de Madrid (UCM)Inglésengopen accesshttp://purl.org/coar/access_right/c_abf2info:eu-repo/semantics/openAccessoai:docta.ucm.es:20.500.14352/714942026-06-02T12:44:21Z
dc.title.none.fl_str_mv Intrinsic structure perspective for MIPS interfaces in two-dimensional systems of active Brownian particles
title Intrinsic structure perspective for MIPS interfaces in two-dimensional systems of active Brownian particles
spellingShingle Intrinsic structure perspective for MIPS interfaces in two-dimensional systems of active Brownian particles
Chacón, Enrique
539.1
Pressure
Física nuclear
2207 Física Atómica y Nuclear
title_short Intrinsic structure perspective for MIPS interfaces in two-dimensional systems of active Brownian particles
title_full Intrinsic structure perspective for MIPS interfaces in two-dimensional systems of active Brownian particles
title_fullStr Intrinsic structure perspective for MIPS interfaces in two-dimensional systems of active Brownian particles
title_full_unstemmed Intrinsic structure perspective for MIPS interfaces in two-dimensional systems of active Brownian particles
title_sort Intrinsic structure perspective for MIPS interfaces in two-dimensional systems of active Brownian particles
dc.creator.none.fl_str_mv Chacón, Enrique
Alarcón, Francisco
Ramírez, Jorge
Tarazona, Pedro
Valeriani, Chantal
author Chacón, Enrique
author_facet Chacón, Enrique
Alarcón, Francisco
Ramírez, Jorge
Tarazona, Pedro
Valeriani, Chantal
author_role author
author2 Alarcón, Francisco
Ramírez, Jorge
Tarazona, Pedro
Valeriani, Chantal
author2_role author
author
author
author
dc.contributor.none.fl_str_mv Universidad Complutense de Madrid
dc.subject.none.fl_str_mv 539.1
Pressure
Física nuclear
2207 Física Atómica y Nuclear
topic 539.1
Pressure
Física nuclear
2207 Física Atómica y Nuclear
description Suspensions of active Brownian particles (ABPs) undergo motility-induced phase separation (MIPS) over a wide range of mean density and activity strength, which implies the spontaneous aggregation of particles due to the persistence of their direction of motion, even in the absence of an explicit attraction. Both similarities and qualitative differences have been obtained when the MIPS is analysed in the same terms as a liquid-gas phase coexistence in an equilibrium attractive system. Negative values of the mechanical surface tension have been reported, from the total forces across the interface, while stable fluctuations of the interfacial line could be interpreted as a positive capillary surface tension; in equilibrium liquid surfaces, these two magnitudes are equal. We present here the analysis of 2D-ABP interfaces in terms of the intrinsic density and force profiles, calculated with the particle distance to the instantaneous interfacial line. Our results provide new insight into the origin of MIPS from the local rectification of the random active force on the particles near the interface. As has been reported, this effect acts as an external potential that produces a pressure gradient across the interface, such that the mechanical surface tension of the MIPS cannot be described as that of equilibrium coexisting phases; however, our analysis shows that most of that effect comes from the tightly caged particles at the dense (inner) side of the MIPS interface, rather than from the free moving particles at the outer side that collide with the dense cluster. Moreover, a clear correlation appears between the decay of the hexatic order parameter at the dense slab and the end of the MIPS as the strength of the active force is lowered. We show that, using the strong active forces required for MIPS, the interfacial structure and properties are very similar for ABPs with purely repulsive interactions (the Weeks-Chandler-Andersen-Lennard-Jones (WCA-LJ) model truncated at its minimum) and when the interaction includes a range of the LJ attractive force.
publishDate 2022
dc.date.none.fl_str_mv 2022
2022-03-30
2022
2022-03-30
dc.type.none.fl_str_mv journal article
http://purl.org/coar/resource_type/c_6501
dc.type.openaire.fl_str_mv info:eu-repo/semantics/article
format article
dc.identifier.none.fl_str_mv https://hdl.handle.net/20.500.14352/71494
url https://hdl.handle.net/20.500.14352/71494
dc.language.none.fl_str_mv Inglés
eng
language_invalid_str_mv Inglés
language eng
dc.rights.none.fl_str_mv open access
http://purl.org/coar/access_right/c_abf2
dc.rights.openaire.fl_str_mv info:eu-repo/semantics/openAccess
rights_invalid_str_mv open access
http://purl.org/coar/access_right/c_abf2
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv Royal Soc Chemistry
publisher.none.fl_str_mv Royal Soc Chemistry
dc.source.none.fl_str_mv reponame:Docta Complutense
instname:Universidad Complutense de Madrid (UCM)
instname_str Universidad Complutense de Madrid (UCM)
reponame_str Docta Complutense
collection Docta Complutense
repository.name.fl_str_mv
repository.mail.fl_str_mv
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score 15,300719

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